Achberg is a municipality located in the Argen river on the border between Baden-Württemberg and Bavaria in the southern part of the Ravensburg district.

The municipality of Achberg consists of the parish villages Esseratsweiler and Siberatsweiler as well as the hamlets Doberatsweiler, Pechtensweiler, Gunderatweiler, Liebenweiler, Baind, Bahlings, Isigatweiler, Regnitz, and Duznau.

Esseratsweiler and Siberatsweiler, along with their associated areas, historically belonged to the ecclesiastical jurisdiction of the Archdiocese of Freiburg in Hohenzollern, but pastorally have been under the care of the Diocese of Rottenburg-Stuttgart since 2007.

Explanation of the Coat of Arms: Before 1968, the municipality bore, on a golden shield, an eight-pointed black star above a green trimount.

The unusual eight-pointed mount was based on a folk etymological interpretation of the place name,[9] while the star likely served only as a filler.

On 1 January 1969, the municipality adopted the current coat of arms, which is symbolized by the representation of the trimount with the wavy stripe, indicating "mountain at the Ach."

The black-and-white colors of the flag also recall Achberg's affiliation with Hohenzollern from 1806 to 1968, most recently as an exclave of the Sigmaringen district.